61 lines
1.3 KiB
Python
61 lines
1.3 KiB
Python
import fileinput
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from collections import deque
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map = []
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start_pos = None
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end_pos = None
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for y, row in enumerate(fileinput.input(mode="rb")):
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row = row.strip()
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if not row:
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continue
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r = []
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for x, col in enumerate(row):
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match col:
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case 83:
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start_pos = (x, y)
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r.append(0)
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case 69:
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end_pos = (x, y)
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r.append(25)
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case _:
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r.append(col - 97)
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map.append(r)
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assert start_pos is not None
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assert end_pos is not None
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part1, part2 = None, None
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trace: tuple[tuple[int, int], ...] = ()
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stack = deque([(0, end_pos, trace)])
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visited = set()
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while stack:
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h_, (x, y), trace = stack.popleft()
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if x < 0 or x >= len(map[0]) or y < 0 or y >= len(map) or (x, y) in visited:
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continue
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h = map[y][x]
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if h - h_ < -1:
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continue
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if part1 is None and (x, y) == start_pos:
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part1 = len(trace)
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if part2 is None and h == 0:
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part2 = len(trace)
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if part1 is not None and part2 is not None:
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break
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visited.add((x, y))
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trace = trace + ((x, y, h),)
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stack.append((h, (x - 1, y + 0), trace))
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stack.append((h, (x + 1, y + 0), trace))
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stack.append((h, (x + 0, y - 1), trace))
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stack.append((h, (x + 0, y + 1), trace))
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else:
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assert False
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print(part1, part2)
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